When scientists talk about the cryosphere, they mean the places on Earth where water is in its solid form, frozen into ice or snow. Read more ...

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Geocryology and Geocryological Zonation of Mongolia

Summary

The map of Geocryology and Geocryological Zonation of Mongolia was digitized from the National Atlas of Mongolia (Sodnom and Yanshin, 1990). The data set depicts the distribution and general properties of permafrost and seasonally frozen ground and locations of specific cryogenic phenomena in Mongolia. Two plates were digitized. One plate, at a scale of 1:12,000,000, depicts four general geocryological zones: continuous and discontinuous permafrost, insular and sparsely insular permafrost, sporadic permafrost, and seasonally frozen ground. The second plate, at a scale of 1:4,500,000, depicts 14 different terrain classifications determined according to elevation, mean annual air temperature, permafrost thickness and thaw depth, and seasonal frozen ground freeze depth. The locations of six specific cryogenic phenomena are also included: perennial frost mounds, icings, thermokarst, cryogenic landslides, solifluction, and cryogenic planation. Data are available via FTP as ESRI shapefiles.

ESRI shapefiles in the general format as follows:*.dbf = attribute data*.prj = projection information*.shp = feature geometry*.shp.xml = ESRI/FGDC formatted metadata (This file is optional and does not include all the information in this document)*.shx = the shape index, which stores an index to the feature geometry*.sbx, *.sbn = spatial index of the features

Acknowledgements

This work was supported by the International Arctic Research Center, University of Alaska Fairbanks, under the U.S. NSF cooperative agreement OPP-0327664.

2. Detailed Data Description

File Format and Naming Convention

Files are in ESRI shapefile format. A shapefile consists of several actual files that are usually considered as one file by most GIS applications. The following file types are included:

*.dbf = attribute data*.prj = projection information*.shp = feature geometry*.shp.xml = ESRI/FGDC formatted metadata (This file is optional and does not include all the information in this document)*.shx = the shape index, which stores an index to the feature geometry*.sbx, *.sbn = spatial index of the features

The data set consists of the following shapefiles:

cryo_landslide.shp = point locations of cryogenic landslidescryo_planation.shp = point locations of cryogenic planationdig_country_bnd.shp = digitized country boundary polygon from the 1:4,500,000 mapdig_lakes.shp = digitized lake polygons from the 1:4,500,000 mapdig_streams.shp = digitized stream vectors from the 1:4,500,000 mapgeocryo_regions.shp = digitized geocryological region polygons from the 1:12,000,000 map. See the attribute description below.geocryology.shp = digitized polygons of areas with detailed geocryological information from the 1:4,500,000 map. See the attribute description below.icings.shp = point locations of icingsper_frost_mound.shp = point locations of perennial frost moundssolifluction.shp = point locations of solifluctionthermokarst.shp = point locations of thermokarst

Projection

Parameters and Attributes

Parameters include the locations of thermokarst, icings, perennial frost mounds cryogenic landslides, solifluction, and cryogenic planation. The geocryo_regions.shp file shows the location of four geocryological regions: continuous and discontinuous permafrost, insular and sparsely insular permafrost, sporadic permafrost, and seasonal frozen ground. These regions are labeled in the shapefile attribute table. This classification scheme is not defined. It is unclear how it relates to the International Permafrost Association definitions for permafrost regions. The geocryology.shp file includes a more detailed 14-level classification scheme shown in the table below. The values in the table are included in the attribute table of the shapefile.

Value

Terrain

General Landform

Thaw Depth (m)

Freeze Depth (m)

Mean Annual Air Temperature (°C)

Prevalent Permafrost Thickness (m)

1

permafrost ("pf")

slopes and watersheds ("hi")

1.0 - 3.5

-

-2 - -5

> 100 ("3")

2

permafrost ("pf")

slopes and watersheds ("hi")

1.5 - 4.5

-

0 - -2

< 100 ("2")

3

permafrost ("pf")

valley bottoms and basins ("lo")

1.3 - 2.5

-

-2 - -5

> 100 ("3")

4

permafrost ("pf")

valley bottoms and basins ("lo")

1.5 - 4.0

-

0 - -2

< 100 ("2")

5

permafrost ("pf")

valley bottoms and basins ("lo")

1.7 - 3.0

-

0 - -1

< 50 ("1")

6

seasonal frozen ground ("sfg")

slopes and watersheds ("hi")

-

3.0 - 4.5

0 - +2

-

7

seasonal frozen ground ("sfg")

slopes and watersheds ("hi")

-

2.5 - 4.5

0 - +3

-

8

seasonal frozen ground ("sfg")

slopes and watersheds ("hi")

-

2.0 - 4.1

+2 - +5

-

9

seasonal frozen ground ("sfg")

slopes and watersheds ("hi")

-

2.0 - 4.0

+3 - +10

-

10

seasonal frozen ground ("sfg")

valley bottoms and basins ("lo")

-

2.5 - 5.0

0 - +2

-

11

seasonal frozen ground ("sfg")

valley bottoms and basins ("lo")

-

2.2 - 5.0

0 - +3

-

12

seasonal frozen ground ("sfg")

valley bottoms and basins ("lo")

-

1.6 - 4.5

+2 - +5

-

13

seasonal frozen ground ("sfg")

valley bottoms and basins ("lo")

-

2.0 - 4.5

+3 - +10

-

14

seasonal frozen ground ("sfg")

valley bottoms and basins ("lo")

-

2.5 - 4.0

+5 - +10

-

Sample Images

These figures show examples of geocryology.shp and geocryo_regions.shp using a color scheme that approximates that used in the original paper maps. Click on the image for a larger version.

An analysis of the digital versions of the maps produces different percentages that can vary as much as two percentage points depending on whether lake area is included in the analysis. Furthermore, Sodnom and Yanshin's table gives the total area of Mongolia as 1,565,000 km2 while the calculated area of geocryo_regions.shp is 1,611,023 km2. The World Factbook (CIA 2005) lists the area of Mongolia as 1,564,116 km2 and the Digital Chart of the World (ESRI 1992) indicates 1,565,866 km2. Some error was inevitably introduced as part of the digitization process. The lack of information of how the original maps were produced and how the regions are defined adds additional uncertainty. This data set is best used for broad scale analysis and comparisons and is unsuitable for very fine scale spatial analysis.

Related Data Collections

4. Data Acquisition and Processing

Data Acquisition Methods

The maps were digitized by first scanning the images at high resolution and then rectifying the image to the Digital Chart of the World's boundary map of Mongolia (ESRI 2005). No projection information was available on the original map, so the projection was chosen to best rectify the map.